DE1696277A1 - Stabilized cellulosic material - Google Patents

Description

Stabilized cellulose material »■ -" '_ ■

The invention relates to thermally stabilized gelluloa material and in particular on the stabilization of cellulose. fibers that are used as insulating material in electrical devices »

The thermal stability of the electrical insulation in electrical devices is a limiting factor for their structure. In many cases, the electrical insulation consists completely or partially of Cellulosimaterialien, such as paper, cardboard, cotton, linen or wool, bis Srenztemperatu, r for this structure for Celluloseisöliermaterialien is about 105 ⁰ C. When higher Binsatztemperaturen are desired, the time other insulation materials are used, which have a higher thermal stability «Bieae sind abej? also more expensive al ^ "cellulose.

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ORIGINAL BATHROOM.

67/8223

Cellulose materials deteriorate relatively quickly at temperatures of over 100 ^° C. when they are in contact with air. They deteriorate even more at such temperatures when they are in contact with liquid dielectrics, such as transformer oil, which can be oxidized. Electrical devices containing cellulose insulation containing _t ~ can not be generally used at temperatures above 105 ^0C.

A factor for determining the maximum temperature at which electrical devices can be used without danger is the

Ability of cellulose isolation the great mechanical and electrical Maintain strength after being at such maximum temperatures was used. This applies to both electrical insulation tion »that is in contact with a liquid dielectric or immersed in it, as well as for cellulose isolation that is in contact with air is.

It is known that by the addition of about 3 1 * urea to oil, based on the total weight of the oil to the paper is imparted an improved thermally "stability, that a paper has with urea stabilized at 125 ° C for approximately the same lifetime as a non-stabilized at 100 ^° C. The service life of the paper is measured by the remaining tensile strength and the increased resistance.

It has been found that the thermal stability of cellulose material, In particular, electrical insulating paper can be greatly increased by pretreating the paper with at least one 2,4-diamineQ-s-triazine compound. In some cases it's special beneficial to this organic compound during manufacture Ί? Add paper to at least 0.1 to 10 wt .- ^ in the paper

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to create a connection. The paper is more resistant to high Temperatures. According to the invention, the cellulose material with a or more of the sym.triazines are impregnated. This can be either during manufacture in the paper machine or during finishing of the paper. .

The cellulose insulating material stabilized according to the invention is particularly suitable for use in electrical devices because of the improved thermal stability at elevated temperatures. This applies to a greater extent to Kraft paper, which is used as an electrical insulating material and is then more stable when it is in contact with air or immersed in a dielectric liquid present in an electrical device. It has been shown that the service life of the paper or insulating material stabilized according to the invention is the same as that of untreated paper.

The stabilized according to the invention is particularly advantageous Cellulose insulation used in an electrical device with an electrical reverse that generates heat during operation. the Celxuloöeisolierung is in connection with the winding in the device and it loses over time with the occurring temperatures' of physical text. Furthermore, a liquid dielectric, which consists essentially of petroleum oil »on the winding applied and this is in contact with the cellulose insulation, to dissipate the heat developed in it and the cellulose insulation is impregnated with a derivative of 2,4-diamino-s-triazine with various substituents in the 6-position ..

Me drawing illustrates the invention. It shows a graphic Representation of the increasing loss of burst strength during

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of aging. The percentage retention of the initial burst strength according to Mullen is plotted against the time index.

The thermal stability of the electrical insulation, which is wholly or partly made of cellulose materials, such as e.g. Paper, paper board, cotton, linen or wool can be improved according to the invention by treatment with sym. Triazines. With such a treatment, the life of the material can be increased by more than three times the life of untreated material which has been subjected to the same conditions. For this purpose, a cellulose material, for example kraft paper, is impregnated by immersion in a solution which contains at least one derivative of 2,4-diamino-s-triazine with various substituents in the 6-position. Such substituted derivatives of 2 ₁ .4 ~ diamino-s-triazines are referred to in the trade as guanamines. The general formula of such guanamines is:

Vr-,

S V. - ..

where H is a monovalent non-acidic organic Se · &% with at least one carbon atom, such as aS -O ₁₁ Hp * in iauroguattÄmin »-OH, in acetoguanamine, OgHg in benzoguanamine» a heterocyclic radical, such as, for example, -CeH ^ N in jfieotinoguanamine and * Ö &> - i ^a Succinoguönfiuain It is assumed that the last-mentioned derivative contains two sy au triazine rings, because ea is made from sulceinonitrile, which confers the two-functionality. The general formula for succinoguanamine is

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, η 'CHg

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Cellulose isolations »which are about 4 Sew» - <· # Lauroguanamini Acetoguananiin, Benzoguananiin, Nicotiiioguanaisin and / or Succinoguananiin. included, erwieaeji sicb ala particularly cheap. The various sym. Irritating solutions are used to impregnate electrical Kraft paper * Ba can for example be dipped into the solution or the solution can be sprayed onto the paper. The solvents used to prepare the solution are generally different depending on the "sym" iriazine used. Pur the choice of solvent, the Leichtigkeitr is crucial with which it sym a sufficient amount. Friazine dissolves, so that when the paper treated ttlii later dried "it is at least 0.1 i» and preferably 0.5 We TO? S Quanaaindertvate, based on the weight of the oily cellulosic material. It is particularly favorable a level of about 4 weight 5 (sym.Triazin, based on t ^ aöfcenes behandeltesi tarier "Katürlich can dive or 3prühbehandlung if erforderliah also be repeated several _times: UAE ^ s reserves to aym.Triaain in the desired amount to increase · j

Solvents suitable for the production of the auroguanamir ^ solutions are acetone, methanol, methyl ethyl ket ^ ir /. and denatured Xthy 1-

Alcohol, lauroguanamine dissolved in acetone with a content of approximately

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1.3 wt. #, In methanol at approximately 2 wt. Ft., In ethyl ethyl ketone to about 2.3 wt .- # and in denatured ethyl alcohol to about 8.2 wt. 5 *. Denatured ethyl alcohol is higher because of, tines Losungavermögena for Lauroguanaain the preferred® solvent for aym.triazine, when it comes to impregnation of electrical grade kraft paper is used, Kraft papers, which in an 8 ff solution of Lauroguanamine dipped in denatured ice ethyl alcohol and later dried have increased their weight by 4 * 3 6ew * ~ # (dry base) presumably as a result of the addition of beiizoguaiiaminsu

It has been found that acetoguanamine is poorly soluble in methanol, methyl ethyl ketone, denatured ethyl alcohol, dimethylformamide and cold water. However, it was readily soluble in hot water and in a hot mixed solution. from 50 parts by volume of denatured ethyl alcohol and 50 parts by volume of distilled water. The latter mixture of solutions holds about $ 5> acetoguanamine in solution, based on the weight of the solution when cooled to room temperature. The preferred composition of acetoguanamine is approximately 5 parts by weight of acetoguanamine dissolved in 95 parts by weight of a fine mixture of 50 parts by volume of denatured ethyl alcohol and 50 parts by volume of distilled water.

It has been found that benzoguanamine is relatively insoluble in acetone, benzene, cyclohexanone, denatured ethyl alcohol, methanol, and methyl ethyl ketone. However, if Bimethylformaaii added to Hethyläthylketca in fractions of a Gawiciitateil Diaaethyliormamid to two parts by weight of methyl ethyl ketone * solved the - \ resulting Löeungsgemiseh Benzoguaiiamin bia a Üehalt

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about 8.1 ffc based on the weight of the solution. It was found that kraft paper * which by 6.9 Sew "immersed in AEIE aforementioned solution and were subsequently dried, their weight - have ^ ₉ related increases in the dried paper before Bsliandlung. The preferred composition of the bensoguaiaaiin solution for impregnating the paper with 4 i " tier compound by dipping is that" it contains about 5 parts by weight of benzoguaziaaiia dissolved in .95 parts of the mixed solution containing about 31 "? Sewielit parts Birnethylförataoiä and about 63 * 3 parts by weight Methylltlijlfcetosv - "■. -; -. -V;" ■ """*

It was found that nicotinoguanaain was relatively insoluble in hot or cold methanol, helium or cold methyl ethyl ketone, and hot or cold water Solution at Kirnetrf ^ et ^ tittur * -Ss it was also found that it is soluble in dimethylfοraaasiä au at least % Öew «HÄ at room temperature. The solubility at higher Pros levels was not investigated. Sine BUi..isäsnateilende improvement of the thermal stability voa Kraftpagier hurdle received, if the Kraft paper with Nicotinoguanaain iaprägnicrt mirde durcb. Immerse in a solution containing 5 parts by weight of the compound ia W $ Qiten ^^ Biiaethylformamide,

It has been found that snccinoguanamine is relatively insoluble in hot or cold methanol or in hot or cold methyl ethyl ketone. It was readily soluble in hot water and only sparingly soluble in cold water and denatured ethyl alcohol dimethylformamide dissolved at least 5% by weight of succinoguanamine at room temperature; solid concentrations with higher percentages were not carried out. A satisfying

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de Improvement of the thermal stability of the Kraft paper with the The aforementioned nicotinoguanamine was achieved when the paper was impregnated was made with succinoguanamine by dipping in a solution containing 5 parts by weight of the compound in 95 parts of formamide.

The treated paper samples were first dried for each immersion in room air, and then the last traces of solvent removed by three hours of heating the sample in a forced air oven at about 125 G ^0.

After cooling to room temperature, the impregnated paper was heated to about 15O ⁰ C, to be able to perform the aging test in transformer oil for various times up to 42 days. At certain times, certain samples were removed and the Mullen burst strength was determined. The aging tests were carried out on treated and untreated paper samples and they are shown for the various solutions used in the following table:

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Tabel Q untreated

paper

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Effect of impregnation with a sym.Triaain to the aging of KraJTtpapier under oil at 15O ⁰ C with limited exposure to air

Acetοguanamine Benzoguanamine • Hieptinoguanaaiine SucGinoguanamine

initially 63.3

62.5 74.8 61.0 61.1 63.5

Mullen burst strength in psi

aged 1 day

58.7

59.3 68.4 59.3 56.2 60.8

aged 4 days

12.9

44.5 58.5 49.5 60.0 54.9

aged 7 days

7.8

24.8 53.0 32.8 49.0 49.0

aged 14 days

(B)

7.0 41.0 15.0 38.0 30.0

aged 28 days

(E) 28.8 9.0 23.6 16.2

aged 42 days

17.0 5.5

13.0 9.0

about $ 4> guanamine was present in the treated paper, the (E) test was canceled because the paper was too weak for further testing.

The results of the table are shown graphically in the drawing. In this the percentage retention is the initial one Mullen burst strength in psi plotted against, the time of Aging in days. From the table is the extension of the service life from Kraft paper, which can be seen by incorporating derivatives of 2,4-diamino-s-triazine with various substitutes in 6-position results. Untreated Kraft paper was too soft to use to be able to test after nine days. With the exception of lauroguanamine the sym.Triazine derivatives reached the "end point" of 42 fagen or longer. Treatment with lauroguanamine showed the least effect, which extended the life of Kraft paper to just 15 days.

The invention is illustrated by the following examples:

example 1

50 squares of electrical quality kraft paper, each square in the air 100x100 mm and was 0.1 mm thick, were first dried for 3 hours in a forced air oven at 12O ⁰ C. A solution of approximately 8 parts by weight of lauroguanamine in approximately 92 parts by weight of denatured alcohol was prepared at room temperature. After cooling, the square papers were dipped one at a time in the solution. The immersion time was long enough to completely wet each square of paper. After removing from the solution, the squares were hung to dry in room air. If they dry up, anfühlten, were they returned for another 3 hours in the oven of about 12O ⁰ C to remove all traces of denatured alcohol to.

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After cooling to room temperature, the dried paper squares were placed in a one liter container containing 850 ml of uninhibited transformer oil. Thirty minutes later, two of the papers were taken out. After absorbing excess oil, they were tested by means of the bursting strength - according to Mullen. The average of two values thus obtained was designated as the initial or unaged burst strength. The container and its contents were placed in a closable can that had a tap in the lid that could be opened to allow any gas pressure to be used and which also allowed a limited access of air μ . The can with the open tap was placed in an air circulation ^{oven at approximately 150 °} C. After the can and its contents had reached oven temperature, the tap was closed. The can remained in the oven for 22 hours. The tap was then opened to allow air to enter. The can was taken out of the oven. It could be left at room temperature for two hours. Two squares of paper were then removed and the Mullen burst strength tested to give an average value for one day aging. This process of aging for 22 hours in the oven and 2 hours in room air was repeated daily until the ™ paper squares were too soft and / or too stiff to give meaningful values.

Example 2

In the previous example, equal squares of electrical grade Kraft paper with the other solutions given above treated, namely acetoguanamine, benzoguanamine, nicotinoguanamine and suceinoguanamine. The values obtained for the burst strength

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according to Mullen are those listed in the table.

The deterioration of untreated Kraft paper is believed to be caused by the formation of acidic products and is particularly aggravated by acids produced by oxidation of the Oil are formed. In the oil test described above was the oil oxidizes after heating. The acids become the Attacked cellulose molecules in the paper. This increases the tensile strength of paper diminished. The additives according to the invention delay the acid attack on the cellulose molecules. From the results reported in the table it can be seen that the treated Kraft paper improved thermal Has stability at temperatures up to 150 ° 0 when it is in transformer oil is dived.

Treatment of Kraft paper and other cellulosic materials with Sym.triazine solutions without the application of water produce treated paper products that do not pucker or crack, what special further parts of the gate are.

So it can improve the thermal stability of cellulose insulation material, such as Kraft paper, can be improved by impregnating the paper with an organic solution of 2,4-diamino-s-triazine of use. Such treatment increases the lifespan of paper by more than three times the life of Untreated paper increases, so the paper has high temperatures can be subjected and can also be exposed to hot transformer oil for long periods of time.

6 claims

¹ figure.

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Claims (6)

-T696277 PM ~ 67/8273 Ä claims 1. Stabilized cellulosic material, especially for use in electrical devices that contain a liquid dielectric, characterized in that it contains 0.1 to 10 wt., - $, "based on the Dry weight of the cellulosic material of at least one derivative of 2,4-diamino-s-triazine of the formula H ₉ \ N 0-— C-R d. t / N \ C == H ₂ —N wherein R is a non-acidic monovalent radical with at least one Is carbon atom. 2. Stabilized cellulose material according to claim 1, characterized in that it is acetoguanamine of the formula as a derivative of 2,4-diamino-s-triazine NH ₂ Λ / contains. 3. Stabilized cellulose material according to claim 1, characterized in that it is a derivative of 2,4-diamino-s-triazine benzoguanamine of the formula - 13 - Td / De 109 8 46/037 3 JH NH ₂ Nj - N contains. . 4. Stabilized cellulose material according to claim 1, characterized in that that it is a derivative of 2,4-diamino-s-triazine nicotinoguanamine the formula ".. NH ₂ G N Y / H ₂ NC ^ nrN contains 5. Stabilized cellulose material according to claim 1, characterized in that that, as a derivative of 2,4-diamino-s-triazine, it is a compound of the formula C-N, C-N N CNH ₀ N. ^X CNH H ₂ NC = NH ₂ N contains. 6. Process for making the stabilized cellulosic material
according to claim 1, characterized in that at least one
Derivative of 2,4-diamino-s-triazine of the formula - 14 - Td / De 109846 / QIII ₅ ^ BAD SS * C N H ^N: CR C -: ■; -JT '^; H ₂ N ^ incorporated into cellulose during the manufacture of the paper will. "..., - - 15 - Td / De 109848/0373 BAD OBiOtNAL Blank page